1. Field of the Invention
The process of this invention is related to that claimed in U.S. Pat. No. 3,987,068 and filed in Class 260/396 R.
2. Description of the Prior Art
P-benzoquinone is an intermediate in the formation of hydroquinones which are useful as antioxidants, reducing agents, polymer intermediates, etc.
U.S. Pat. No. 3,987,068 concerns a process for making p-benzoquinone wherein phenol is contacted with a source of oxygen in the presence of a copper salt catalyst in a nitrile solvent such as acetonitrile. The patent contains no suggestion of an acetonitrile/methanol cosolvent system.
U.S. Pat. No. 3,210,384 teaches the making of a tetrasubstituted dibenzoquinone by oxidizing disubstituted phenol in the presence of a copper salt catalyst in a solvent comprising acetonitrile. Cosolvents such as methanol, ethanol, acetone, trichloroethylene, etc., can be employed "providing they do not interfere or enter into the oxidation reaction" (column 6, lines 49 and 50).
U.S. Pat. No. 3,870,731 teaches the oxidation of phenol to p-benzoquinone in the presence of copper salt catalysts, a catalyst promoter, and methanol. The patent does not disclose acetonitrile solvent.
U.S. Pat. No. 3,859,317 teaches the cobalt and manganese-catalyzed oxidation of phenol to p-benzoquinone in the presence of a solvent such as methanol. Acetonitrile is not disclosed.
There is nothing in the prior art to suggest the improvement in yield and productivity made possible by employing the specific acetonitrile/methanol cosolvent system described herein.